What exactly does SQLite's “NO ACTION” foreign key constraint do and how is it different from “RESTRICT”?

Question

The documentation says:

Configuring \"NO ACTION\" means just that: when a parent key is modified or deleted from the database, no special action is

Answer 1

The introducing paragraph says:

If an action is not explicitly specified, it defaults to "NO ACTION".

This is the normal action.

Furthermore:

The difference between the effect of a RESTRICT action and normal foreign key constraint enforcement is that the RESTRICT action processing happens as soon as the field is updated - not at the end of the current statement as it would with an immediate constraint, or at the end of the current transaction as it would with a deferred constraint.

If you're testing with a single-statement transaction that changes just one record, you will not see any difference between NO ACTION and RESTRICT.